International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.

1. International Journal of Computational Engineering Research||Vol, 03||Issue, 6||
www.ijceronline.com ||June||2013|| Page 54
A Survey on Security in Multihop Wireless Network
Kritika Jain1
, Anurag Joshi2
, Pawan Prakash3
,
1
Dept. of Computer Science and Engineering, Gyan Vihar University, Jaipur, Rajasthan, India.
2
Dept. of Information Technology, Sikkim Manipal University, Gangtok, Sikkim, India.
I. INTRODUCTION.
Routing is the technique used to move a data packet from the sender to receiver. It enables the
messages to pass from one node (computer) to another leading it to finally reach the destination. Every data
packet contains within it the set of information including what is it, where it is coming from (sender’s IP
address) and where it is going (receiver’s IP address). The device called as router is used to perform routing in a
network. While we consider routing in Multihop wireless networks, it becomes immensely necessary to find the
optimal and most secure routing protocols out of the existing ones. The aim of our study is to secure these
multihop wireless network protocols. We have tried to first discuss the various routing protocols and various
security attacks on these routing protocols. Then after discussing attacks on routing protocols, we have
identified the security measures that could help to increase the reliability of the protocols.
II. LITERATURE REVIEW.
There are various numbers of researchers who proposed several architectures and protocols to secure
the Multihop wireless networks.Srdjan Capkun, Levente Buttyan and Jean Pierre Hubaux [1] successfully
presented SECTOR which is the mechanism to prevent the wormhole attacks and thus to secure routing
protocol. SECTOR was based on distance bounding technique, on one-way hash claims and on Merkle hash
trees.A new protocol called as BSMR was proposed by Reza Curtmola and Cristina Nita-Rotaru [2] that can
withstand insider attacks from colluding adversaries.Douglas, Daniel, Benjamin and Robert [3] concluded in
their work that the shortest path algorithm id not enough to increase the performance of multihop wireless
networks.Jorjeta G. Jetcheva and David B. Joshnson [4] presented the informal design and they evaluated
ADMR protocol.Yauchao Zhang and Yuguang Fang [5] successfully addressed the multihop wireless mesh
network security. They also proposed ARSA which is an attack resilient security architecture for multihop
wireless mesh networks.
III. ROUTING PROTOCOLS FOR MULTIHOP WIRELESS NETWORKS.
In order to enable the communication between the routers, routing protocols disseminates information
about selecting routes between nodes in a network.
3.1 Types of routing protocols.
“Figure 1. Types of Routing Protocols”
ABSTRACT:
Multihop wireless networks are the type of networks which require two or more wireless hops to
deliver the information from the source to destination. Thus finding an optimal and most secure path to
route the data is the major challenge. There are various routing protocols proposed for Multihop
wireless networks but most of them are either insecure or informal method of reasoning is used to
analyze their security.In this paper, we aim to identify the security measures that could increase the
security of routing protocol.
KEYWORDS- Routing, Routing protocols, Adversary, Security attacks, Authentication, Node disjoint
paths.

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3.1.1 Dynamic Source Routing.
DSR protocol [6] is a type of on-demand routing protocol which is designed for use in multihop
wireless network. it is self configuring protocol which eliminates the need for an established network
infrastructure.
DSR follows two main mechanisms:
 Route discovery
 Route maintenance
These mechanisms work together to discover and maintain routes in a wireless network. When the
ROUTE REQUEST reaches the destination node, the ROUTE REPLY message is generated. The destination
requires a route or the route record in the ROUTE REQUEST message header.
Route maintenance phase is initiated whereby the route error packets are generated at a node. Then the
erroneous hop is removed from the node’s route cache. All routes that contain the erroneous hop are truncated
and again route discovery phase is initiated.
“Figure 2. Foot note: DSR route discovery”
“Figure 3. Foot note: DSR Route Reply path”
3.1.2 Adhoc On-Demand Distance Vector Routing Protocol.
AODV is a reactive routing protocol which is capable of both unicast and multicast routing.

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“Figure 4. Foot note: AODV route discovery”
 When source sends data to an unknown destination it broadcasts a Route Request (RREQ) for that
destination.
 When intermediate nodes receive Route Request (RREQ) a route to the source node is created.
 When RREQ reaches the destination node it generates a Route Reply (RREP) in a unicast hop by hop
mode.
 Each intermediate node creates a route from destination to source during the propagation of RREP.
 Finally when RREP reaches the source, it tracks the route from destination to source and begin sending the
data.
 The operation is similar to that of DSR but the nodes maintain routing tables instead of route caches.
“Figure 5. Foot note: AODV Route Reply Path”
3.1.3 Position based Greedy Forwarding.
Position based routing or geographic routing [7] is a type of routing protocol that is based on the
information regarding the geographical position. Mainly proposed for wireless network is based on the
assumption that:
 Nodes are unaware of their own and their neighbor’s position.
 The information about the position of the destination node is contained in the packet header.
In position based greedy forwarding protocol the packet is forwarded to the neighbor who is closer to the
destination than the forwarding node.

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IV. ATTACKS ON MULTIHOP WIRELESS NETWORKS.
The multihop wireless networks are wireless are widely accepted and its applications are increasing day
by day. But the security of these networks is becoming a major key challenge in the wide-scale deployment of
these networks.In simple and general context, an adversary is one’s opponent in a contest, conflict or dispute.In
the term of wireless network, an adversary is a node that opposes or attacks the security of the network and
leading to an insecure communication in the network.These security attacks aim to increase the control of these
adversary nodes over the communication between some nodes in the network. These attacks tend to degrade the
quality of the network services and also increase the resource consumption.Adversaries are not physically
present but aim to corrupt the legitimate nodes by launching attacks from regular devices.
3.2 Types of Attacks.
The various types of security attacks are listed below:
 Route disruption
 Route diversion
 Creation of incorrect routing state
 Generation of extra control traffic
 Creation of a gray hole
3.2.1 Route Disruption.
In the route disruption attack the adversary prevents a route from being discovered between two
connected nodes. The main objective of this attack is to degrade the quality of network services. The two
connected nodes cannot communicate directly and therefore a route is followed that has the adversarial control.
The attack mechanisms are:
 Dropping of Route Request or Route Reply messages
 Forging route error messages
 The dropping of control packet
 Wormhole attack
3.2.2 Route Diversion.
Route diversion attack leads to the establishment of the routes which are different from the ones that
the protocol would establish due to the interference of the adversary. The adversary aims to achieve that the
diverted routes should have its control over the link so that it can eavesdrop or modify the data that is been sent
between the victim nodes.
It also has side effects of increase in resource consumption, overloading the network links and delay in the
delivery of the data.
The attack mechanisms are:
 Modifying or dropping control messages
 Setting up a wormhole/tunnel
3.2.3 Creation of incorrect routing states.
In this attack, the insecure and adversary nodes are appeared to be secure and the state appears to be
correct but in fact they are not. So when the data packets are routed using the infected state they never reach
their desired destination because of these corrupted nodes.
This can be achieved by modifying, spoofing, forging or dropping of control packets.
“Figure 6. Creation of incorrect routing state in DSR”
The route specified by protocol is:
A = *: [RREQ, id, A, H ;()]
From the figure it is been clear that the route (A, D, F, H) does not exist.
Node B being an attacker creates an incorrect route:
B  A: [RREP, <src route>, A, H; (D, F)]

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3.2.4 Generation of extra control traffic.
This attacks aims at injecting spoofed control packets into the networks. Spoofing is the technique of
masquerading others by modifying or falsifying data resulting in gaining illegitimate advantage.
It leads to the increase in consumption of resources by flooding the illegitimate control packets in network.
3.2.5 Setting Up a Gray Hole.
Gray hole [9] attacks the network by leading the nodes to drop the packets selectively. This attack leads
to the data to be either malicious or unnecessary by dropping all UDP packets while forwarding TCP packet or
by dropping packets by probabilistic distribution.
Gray hole is actually an attacker node but behaves as a correct one. Therefore, it becomes very difficult to
identify the attacker node in the network.
V. SECURING MULTIHOP WIRELESS NETWORK ROUTING PROTOCOL.
After discussing several attacks that could degrade the quality of the network, we aim to list out various
security countermeasures that could help to increase the security and prevent these attacks.
4.1 Countermeasures.
 Authenticating control packets
 protection of mutable information in control packets
 Reducing gray holes from the network
4.2.1Authentication of control packets.
In the network whenever a packet is transmitted it has two sets of information: control information and
user data often called as payload. the control information contains the source and destination addresses,
checksums and sequence information. The adversaries often attack the control information of the packet in order
to degrade the quality of service. Control packets should be authenticated by the initiators of the packet using
Message Authentication Code and the authenticity should be verifiable by the destination node.For example
Ariadne which is used to secure the basic version of DSR algorithm.Now when this packet reaches any
intermediate node, that node must be able to verify its authenticity before processing the control packet. After
the verification, the intermediate nodes update their routing state. A Broadcast Authentication scheme must be
employed to verify the authenticity of the nodes.
4.2.2Protection of Mutable Information in Control Packets.
There are certain set of inconstant information that can be altered or changed throughout the network.
This mutable information (hop count, node list etc) is added by intermediate nodes to the control packets before
forwarding it. Since this information is not protected, the adversary could easily attack and modify making it
malicious.To prevent this, each intermediate node before entering or modifying this mutable information should
verify its authenticity. If the node is found authenticated to enter or modify the information then only it is liable
to alter any information.
4.2.3Combating Gray Holes
Gray holes are very difficult to detect in a network. It is much easier to deal with an attacker rather than
detecting it out of the correct nodes. In order to reduce these gray holes, multiple routes should be traced out to
deliver a data packet. It would be preferable if these routes are Node Disjoint paths [10]Node Disjoint Paths
reduces routing overhead and also provides robustness to mobility. To decrease the resource consumption, the
data packet should be coded and then break up into smaller chunks. If a threshold value is set for the number of
chunks then it will prove beneficial to the network. Then these chunks of packet are sent over different routes on
entire network.
CONCLUSION.
As we all are aware that in Multihop wireless networks several intermediate nodes are present which
are also movable. So routing is a major challenge in these networks as it becomes immensely necessary to save
the nodes from the attacks. In this paper, we have discussed various routing protocols and a brief description of
various attacks is also given which can harm the Multihop wireless networks. After discussing these attacks we
have finally discussed several countermeasures that could help to secure the routing protocols from the
adversarial attacks by the authentication.
REFERENCES.
[1.] http://www.enggjournals.com/ijcse/doc/IJCSE10-02-03-04.pdf
[2.] http://dl.acm.org/citation.cfm?id=986862

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[3.] http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2669&context=cstech&sei-
redir=1&referer=http%3A%2F%2Fscholar.google.co.in%2Fscholar%3Fq%3Dbsmr%26btnG%3D%26hl%3Den%26as_sdt%3D
0%252C5%26as_vis%3D1#search=%22bsmr%22
[4.] http://am.csail.mit.edu/papers/grid:hotnets02/paper.pdf
[5.] http://www.cs.rice.edu/~dbj/pubs/mobihoc01-admr.pdfs
[6.] http://nslab.kaist.ac.kr/courses/2007/cs712/security%20misc/1.%20ZHA06%20(ARSA%20-%20An%20Attack-
Resilient%20Security%20Architecture%20for%20Multihop%20Wireless%20Mesh%20Networks).pdf
[7.] http://en.wikipedia.org/wiki/Dynamic_Source_Routing
[8.] http://en.wikipedia.org/wiki/Geographic_routing
[9.] http://www.ijcnwc.org/papers/vol2no62012/2vol2no6.pdf
[10.] http://140.116.247.229/member/Marco/data/On-demand%20Node-
Disjoint%20Multipath%20Routing%20in%20Wireless%20Ad%20hoc%20Networks2.pdf